The present invention relates generally to a spectroscopic analyzer system for analytically examining objects such as intravital tissues and the like of animals and plants with the aid of spectroscopic technique. In particular, the invention concerns a spectroscopic analyzer system for spectroscopically analyzing influences of oxygen concentration, metabolism of medicines, ischemia and the like to intravital objects such as tissues or organs of circulatory systems.
It is well known that intravital pigments of oxidation/reduction type such as, for example, cytochromes carried by mitochondoria in cells of respiratory systems exhibit absorption spectra which are remarkably different between oxidation and reduction types of pigments or cytochromes. By making use of this fact, it is possible to obtain biological or biogenical informations on the cell base through spectroscopical or photometrical detection and quantitative analyzation.
Heretofore, a so-called two-wavelength photometry has been adopted for obtaining the biological or biogenical informations of the type mentioned above. According to the principle of the two-wavelength photometry, measurement is made as to difference in absorption of an object under test between a maximal absorption wavelength (i.e. the wavelength at which difference in absorption between oxidation and reduction types of pigments in concern makes appearance most significantly) and a reference wavelength (i.e. the wavelength which approximates closely to the maximal absorption wavelength and at which difference in absorption is scarcely observed between the oxidation and reduction types). In the two-wavelength photometry, influence ascribable to turbidity of a specimen can be cancelled out because of its substantial equivalency at both wavelengths. Further, by selecting the wavelengths so as to be scarcely influenced by oxidation and/or reduction of other pigments, evaluation of pigment in concern can be effected with a high accuracy.
A typical example of hitherto known spectroscopic analyzer system which is operative based on the principle of the two-wavelength photometry mentioned above is schematically shown in FIG. 1. This system comprises a light source 1 of a predetermined range of wavelengths, a first monochromator 3 for deriving from the light source 1 light ray of a wavelength .lambda..sub.1 at which the maximal absorption by a specimen 2 under test occurs (this wavelength is referred to as the maximal absorption wavelength), a second monochromator 4 for deriving the reference wavelength .lambda..sub.2, a swingably vibrated mirror 5 for projecting alternately the two light beams of the different wavelength .lambda..sub.1 and .lambda..sub.2 to the specimen 2, a photoelectric converter element 6 for converting the light beams transmitted through the specimen 2 into corresponding electric signals, a chopper circuit 7 for separating the output signal from the photoelectric converter element 6 into signal components attributable to the wavelengths .lambda..sub.1 and .lambda..sub.2, respectively, signal conditioning circuits 8a and 8b for amplifying and standardizing output signals from the chopper circuit 7, a differential amplififer 9 for detecting difference between the output signals from the conditioning circuits 8a and 8b, and a recorder 10 for recording data on the basis of the output signal S from the differential amplifier 9 as a function of time.
Circuit configuration of the signal conditioning circuits 8a and 8b is schematically illustrated in FIG. 2. These circuits 8a and 8b comprise, respectively, variable gain amplifiers 11a and 11b for amplifying the incoming signals S.lambda..sub.1 and S.lambda..sub.2 originated, respectively, from the wavelengths .lambda..sub.1 and .lambda..sub.2 to an appropriate level, integrators 12a and 12b for integrating the output signals S.lambda..sub.1 ' and S.lambda..sub.2 ' produced from the variable gain amplifiers 11a and 11b for the purpose of removing noise and increasing sensitivity, and sample/hold circuits 13a and 13b for holding the outputs of the integrators 12a and 12b for a predetermined time. In this connection, it will be noted that the hold time T.sub.1 of the sample and hold circuit 13a provided in the signal conditioning circuit 8a is different from the hold time T.sub.2 of the sample and hold circuit 13b belonging to the signal conditioning circuit 8b, as is graphically illustrated in FIG. 3. This is because the output signals from the signal conditioning circuits 8a and 8b have to be simultaneously applied to the differential amplifier 9.
The hitherto known spectroscopic analyzer system described above however suffers from various and serious drawbacks. First, because a specific component of the specimen 2 in concern requires for the evaluation or identification thereof two light beams of different wavelengths .lambda..sub.1 and .lambda..sub.2, two monochromators 3 and 4 are indispensably required, involving inexpensiveness in respect of hardwares. Besides, every time when use of other wavelengths becomes necessary for identifying other components, interference filters (not shown) inserted in the monochromators 3 and 4 have to be correspondingly replaced by other ones, which requires not only troublesome procedures but renders it impossible to carry out identification of plural components in a continuous manner, involving inefficiency in operation. Further, the specimen 2 can be prepared only through a series of cumbersome procedures such as smashing, differential centrifugation, extraction, purification and containment in a cuvette. The specimen which requires such troublesome preparation can usually provide a single kind of data. For obtaining a number of desired data, the specimen must be prepared in consideration of various particular conditions, thus involving delicate and time consuming procedure as well as high expenditure. Further, difficulty will be encountered in management of stock materials for preparing such specimens. Moreover, the swingable mirror 5 for irradiating the specimen alternately with two light beams of different wavelengths gives rise to an instability in the optical path, providing a cause for generation of noise, to another disadvantage. Besides, use of the integrators 12a and 12b in the signal processing circuits 8a and 8b will integrate also the noise components, which means that the result of measurement is relatively poor in reliability and accuracy. Further, due to analog type configuration of the signal processing circuits 8a and 8b, a desired high speed operation can not be accomplished. Thus, the system on the whole is lacking in reliability and speedy operation.